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Being Alive
Degree of Viral Resistance Not Correlated with Viral Load
Mark Katz, MD, and reported by Jim Stoecker
February 5, 1995
Being Alive 1995 Feb 5: 2

In a recent retrospective study, James Kahn MD went back to the study data of about 100 people who were involved in ACTG 116B/117. This study showed, some years back, that after several years of AZT use, a patient would benefit by switching to ddI (the other antiviral considered in the study). With long term AZT use, we now know that some degree of resistance will develop. But does that resistance mean more virus? If someone is resistant to the drug they are on, will they have higher levels of virus? This is the question that Kahn sought an answer to.

To determine viral load, Kahn made viral DNA copies of the study samples. He found that, contrary to intuition, the degree of resistance did not correlate with the number of viral DNA copies. Something other than just antiviral resistance, it appears, accounts for high levels of virus. In the past, when a patient developed symptoms while on an antiviral, resistance was assumed and the patient was switched to another antiviral. Now, when resistance is suspected, the evolving standard of care is to add another antiviral, rather than simply switch. Dr. Kahn's research seems to support this current approach.